Write a database class in python

Question

For a hobby project I'm doing at the moment I want to write an object oriented python program.But one of the first issue I'm running into is creating a class for my (MySQL) database.

I am trying to use as few packages as possible and I want to try to write the database class by using only pymysql.The problem is that there is an overwhelming amount of libraries and a lack of explanation on writing a good database class in python.

Any suggestions and especially examples would be much appreciated

Answer 1

When having the exact same situation, I found the mysql-connector-python class with which I created a small "model" to call from other classes. This is a cut-down version which shows various db calls. As you can see I have a config class which holds all db authentication info and more).

# dependancy: mysql-connector-python (https://dev.mysql.com/downloads/connector/python/2.1.html)
import mysql.connector
import time
import config
import HTMLParser
import StringIO

html_parser = HTMLParser.HTMLParser()

try:
    connection = mysql.connector.connect( user=config.DB_USER, password=config.DB_PASSWORD,
        host = config.DB_HOST, database=config.DB_DATABASE, unix_socket=config.UNIX_SOCKET)

    cursor = connection.cursor()

except mysql.connector.Error as err:
    logger.log('Database connection failed for '+config.DB_USER+'@'+config.DB_HOST+'/'+config.DB_DATABASE)
    exit()

def get_bad_words():
    sql = ("SELECT word FROM word_blacklist")
    results = execute(sql)
    return results

def get_moderation_method():
    sql = ("SELECT var_value FROM settings "
    "WHERE var_key = %(key)s")
    results = execute(sql, True, {'key':'moderation_method'})
    return results[0]

def current_events():
    sql = ("SELECT count(id) FROM events WHERE event_date >= DATE_SUB(NOW(), INTERVAL 2 hour) AND event_date <= DATE_ADD(NOW(), INTERVAL 5 hour)")
    results = execute(sql, True)
    return results[0]

def insert_social_post(channel, filter_type, post_id, validate, user_name, user_id, user_profile_picture, text, post_date, image_url, state):
    try:
        san_user_name = html_parser.unescape(user_name.encode('utf-8').strip()).decode("utf8").encode('ascii','ignore')
    except:
        san_user_name = html_parser.unescape(user_name.strip())
    try:
        san_text = html_parser.unescape(text.encode('utf-8').strip()).decode("utf8").encode('ascii','ignore')
    except:
        san_text = html_parser.unescape(text.strip())

    insert_post = ("INSERT IGNORE INTO social_posts "
        "(channel, filter_type, post_id, validate, user_name, user_id, user_profile_picture, text, post_date, image_url, state)"
        "VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)")
    execute(insert_post, False, [channel, filter_type, str(post_id), validate,
        san_user_name.strip(), user_id, user_profile_picture, san_text.strip(), post_date, image_url, state], True)

def delete_posts(ids):
    fmt = ','.join(['%s'] * len(ids))
    cursor.execute("DELETE FROM `social_posts` WHERE id IN (%s)" % fmt,
                    tuple(ids))
    connection.commit()

def update_campaigns(campaigns):
    sql = ("UPDATE social_campaigns "
        "SET last_updated = NOW()"
        "WHERE id IN ("+(','.join(str(c) for c in campaigns))+")")
    execute(sql, False, None, True)

def execute(tuple, single = False, args = {}, commit = False):
    cursor.execute(tuple, args)

    if commit == True:
        connection.commit()
    else:
        if single == True:
            return cursor.fetchone()
        else:
            return cursor.fetchall()

def lastrowid():
    return cursor.lastrowid

def close():
    connection.close()

Call upon the class like this:

import db
bad_words = db.get_bad_words()